Technical Field
The present disclosure relates to a semiconductor light source drive device that supplies a current to an assembly formed of series-connected semiconductor light source elements to drive the assembly.
Description of the Related Art
Patent Literature 1 discloses a semiconductor light source drive device that includes a plurality of drive circuits. The drive circuits each include: a constant current circuit that is made up of an operational amplifier, a current sensing resistor, and a FET (field effect transistor); and a voltage detection circuit. An LED (light emitting diode) is connected between drain of the FET and a power source. The voltage detection circuit is connected with both ends of the LED to detect a voltage across the LED. The plurality of drive circuits are connected in parallel with the identical power source. The plurality of voltage detection circuits respectively detect voltages across the LEDs, such that a voltage of the power source is controlled in accordance with the highest one of the detected voltages. This makes it possible to achieve a reduction in loss of a voltage at the FET which is essential in controlling the current. Thus, an efficient semiconductor light source drive device is obtained.